1. Field of the Invention
This invention relates to a method and apparatus for the production of an amorphous alloy article formed by metal mold casting under pressure.
2. Description of the Prior Art
The single roll method, twin roll method, gas atomizing method, etc. are adopted for the production of amorphous alloy because this production generally necessitates a high cooling rate falling in the approximate range of 10.sup.4 -10.sup.6 K/s. The products obtained by such methods are limited in shape to ribbons of foil, fine wires, and particles. This fact constitutes itself a factor for rigidly limiting the field of applications found for amorphous alloy.
Feasibility studies are under way, therefore, regarding a method of producing a formed article of amorphous alloy with a large thickness by shaping an amorphous alloy prepared in the form of powder by some means such as extrusion or impact compression at a temperature not exceeding the crystallization temperature of the alloy. The production by this method, however, requires complicated steps such as sieving the powder, degasing the prepared powder, and preforming the powder prior to the main forming and calls for expensive facilities as well. This method, therefore, is at a disadvantage in inevitably furnishing only expensive products.
As a means for producing a formed article of amorphous alloy by a simple process unlike such powder molding process, published Japanese Patent Application, KOKAI (Early Publication) No. 8-199,318 discloses a method for the production of a rod or tube of a Zr-based amorphous alloy by disposing a forced cooling casting mold having a molding cavity fitted with a molten metal transfer tool on the bottom of a hearth opened on the top side, melting a zirconium alloy containing an element capable of conferring amorphousness on the alloy in the hearth, then extracting the molten metal transfer tool downwardly thereby transferring the melt of the zirconium alloy into the forced cooling casting mold, and rapidly cooling and solidifying the melt of zirconium alloy in the forced cooling casting mold thereby conferring amorphousness on the zirconium alloy.
According to the method described above, however, the cast products have their shapes limited to rods or tubes because their shapes are restricted by the shape of the molten metal transfer tool and the method of extraction of this tool. Further, this method is incapable of substantially pressing the molten alloy because the transfer of the molten alloy is induced simply by the extraction of the molten metal transfer tool. The method, therefore, incurs difficulty in yielding formed articles which are delicate or complicate in shape and the products thereof have room for improvement in terms of denseness and mechanical properties.